Large amounts of water are employed in flotation processes which generally require a water recycle system utilizing active tailing dams and water storage facilities to collect mill water and then subsequently return the water for reuse into the flotation system.
While the system employed enabled total containment of the waste water during certain parts of the season, this was not always possible during the annual spring runoff of melted snow. Thus, the annual rapidly increasing runoff into the tailing system made it necessary to discharge some of the industrial water from the system into surface waters in order to keep the total system in balance.
The water effluent or waste water obtained in molybdenite flotation generally contains small concentrations of heavy metals, such as molybdenum, copper, zinc, iron, and the like, as a result of solubilization during the flotation process. The mill water may also contain combined cyanide in concentrations of less than about two or one part per million introduced in the mill circuit as sodium cyanide which is used as a copper depressant. Such waters present a pollution problem if discharged into the surrounding environment.
It would thus be desirable to provide a waste water treatment process to remove substantially said heavy metals in accordance with the prevailing target amounts for such waters.